Sample mixing and metering apparatus

ABSTRACT

The apparatus includes a sample head adapted to be mounted at a sample pickup station. The head includes a hollow sample pickup probe adapted to be inserted into a sample container at the sample pickup station for extracting a given amount of fluid sample from the container. The pickup probe is movable between a first or sample position and a second or retracted position by means of an air cylinder. A valve mechanism connected to the probe is operable on movement of the probe to the sample position for connecting the probe to a device for withdrawing fluid from the sample container through the probe. The air cylinder not only moves the probe but also, and at the same time, operates the valve mechanism. In the second position the valve mechanism effects fluid connections for mixing a given amount of the fluid sample with another fluid and for simultaneously transferring the mixture to a receptacle.

Jones July 24, 1973 SAMPLE MIXING AND METERING APPARATUS [75] Inventor: Alan Richardson Jones, Miami, Fla.

[73] Assignee: Coult er Electronics, inc l-lialeah,

Fla.

[22] Filed: Oct. 21, 1971 [21] Appl. No.: 191,248

[52] U.S. Cl 73/423 A, 73/422 GC [51] G01n 1/16 [58] Field of Search 73/423 A, 422 GC [56] References Cited UNITED STATES PATENTS 3,419,358 12/1968 Smythe 73/423 A UX 3,489,525 1/1970 Natalson. 73/423 A UX 3,479,880 11/1969 Mutter.... 73/423 A 3,530,721 9/1970 l-lrdina 73/423 A Primary ExaminerS. Clement Swisher V V w my Attorney- 1. Irving Silverman, Thomas R. Vigil et al.

[ 1 ABSTRACT The apparatus includes a sample head adapted to be mounted at a sample pickup station. The head includes a hollow sample pickup probe adapted to be inserted into a sample container at the sample pickup station for extracting a given amount of fluid sample from the container. The pickup probe is movable between a first or sample position and a second or retracted position by means of an air cylinder. A valve mechanism connected to the probe is operable on movement of the probe to the sample position for connecting the probe to a device for withdrawing fluid from the sample container through the probe. The air cylinder not only moves the probe but also, and at the same time, operates the valve mechanism. In the second position the valve mechanism effects fluid connections for mixing a given amount of the fluid sample with another fluid and for simultaneously transferring the mixture to a receptacle.

29 Claims, 8 Drawing Figures PAIENIEU Jul 24% 3. 747. 4 1 2 sum 3 or 4 aft L PATENTED JUL 2 4 I975 saw u 0F 4 SAMPLE MIXING AND METERING APPARATUS BACKGROUND OF THE INVENTION' The invention herein relates to a structure for sampling and mixing liquids and delivering the mixture in a predetermined proportion to a reaction tube for testmg.

In the art of automatic analysis equipment, it is normally required that a sample fluid be diluted with a second fluid in order to provide a diluted sample which is subjected to testing. In the case of particle counting and sizing apparatus, the concentrated sample may be diluted with a nonreactive diluent in order to provide a diluted sample more easily processed in the automatic counting and sizing apparatus. For example, whole blood could be diluted with a saline solution to achieve a diluted blood sample. In the case of a chemical analysis apparatus, the concentrated sample may be mixed with some liquid chemical that is to start a reaction therewith. For example, in blood chemistry apparatus, the undiluted patients serum is diluted with different reagents to commence reactions leading to colorimetric testing of the change in absorbance of the resulting diluted sample.

Examples of known apparatus generally providing for dilution of concentrated sanoles are disclosed in U. S. Pat. Nos. 2,867,355; 3,549,994; and 3,567,389.

In all cases of sampling and mixing, there are certain requirements that must be met. The concentrated sample has to be withdrawn from a body of such sample and a specific volume thereof measured and isolated. The diluting fluid or reagent must be supplied in a predetermined volume so that the proportions of sample to diluent are known. The two liquids must be mixed. The mixture must then be delivered to a location where the diluted sample can be received in a suitable receptacle in which it will be tested.

Accurate measurement and thorough mixing are essential. In addition, the minimum of contamination must be effected between the processing of different samples. I

All of the above comprise problems which the invention herein is intended to solve in a highly effective manner. In addition, however, the apparatus of the invention provides functions which render structure embodying the invention considerably more useful than sampling and mixing devices heretofore known.

In automatic analysis equipment which is intended to process a large number of samples continuously, the samples have to be introduced into the system of the apparatus in one way or another. The introduction of samples manually is known, the cups or vials containing the samples being moved into sample withdrawing position by the operator. The equipment could have a probe, for example, and the operator brings the cup under the probe and moves it vertically to cause the probe to dip into the sample. The operator must then have the skill and knowledge to recognize when the equipment is ready for another sample and he then manually feeds that sample to the probe.

The use of turntables is also known in automatic analysis equipment wherein the samples are disposed in single conduit by means of alternating volumes of diluent and bubbles.

Other methods for withdrawing the samples from their cups are also known.

The invention herein includes a structure which not only performs the withdrawing and mixing and delivering functions, but as well performs two functions which enable considerable automation to be built into automatic analysis equipment which uses structures constructed according to the invention. These two functions comprise the physical movements causing the dipping of the aspirating probe into the sample and the removal of it from the sample. According to the invention, certain passageways and ports are connected and disconnected during these two movements which make the apparatus very simple and effective and enable operation with a minimum of attendance and manual movement of the operator.

The automatic analysis equipment with which the structures of the invention are intended to be used includes a plurality of sample cups spaced apart along a path of movement which, while preferably rectilinear, may be arcuate or circular. There is a plurality of sample aspirating, mixing and delivering devices (often hereinafter called sampling or sample heads) which are located along the path at predetermined positions and which are constructed in accordance with the teachings of the present invention.

SUMMARY OF THE INVENTION According to the invention, there is provided a sample head for use at a sample pickup station, the head including a hollow sample pickup probe adapted to be inserted into a sample container at the sample pickup station for extracting a given amount of fluid sample from the container. The probe is movable between a first or sample position and a second or retracted position and is connected to a valve mechanism operable upon movement of the probe to the sample position for connecting the probe to a device forwithdrawing fluid from the sample container through the probe. A mechanism is provided for moving the probe and simultaneously operating the valve mechanism whereby the valve mechanism is operated by the moving mechanism to connect the probe to the withdrawing means at the same time the probe is moved by the moving mechanism to the sample position.

Preferably, each sample head has a connection to a diluent or reagent pump, a delivery conduit and various connections to sources of vacuum and pressure to cause the operation thereof. The valve mechanism preferably includes a pair of valve blocks which move relative to one another in face to face planar engagement by means of a suitable pneumatically operated cylinderconstituting the moving mechanism which at the same time causes the probe to be dipped downwardly or raised according to the operation of a suitable control mechanism.

When a sample arrives at the sample pickup or aspirating station where one of the sampling heads is located and assuming that the analysis calls for the sample to be mixed with a diluent or a reagent, the probe dips down into the sample, sucks up a quantity of sample, and then withdraws from the cup. During these movements, the diluent, or reagent is first drawn into a pump, second, mixed with a specific volume of sample and third, delivered by means of a conduit or tubing to a reaction tube apart from the sampling head. All of this is done automatically after which the sampling head is ready for the next cup to come along.

In this way, the cups are never disturbed as they are moved along their path. Also, a different head may be used for each different kind of test and a minimum of sample and diluent or reagent is wasted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view showing a system for automatically aspirating a sample, mixing it with a diluent or reagent and then depositing it in a reaction tube;

FIG. 2 is a side elevational view of the sampling head of the invention with portions broken away to show the details thereof, the head being shown in its two positions',

FIG. 3 is a fragmentary top plan view of the head;

FIG. 4 is a fragmentary sectional view taken along the line 44 of FIG. 2 and in the indicated direction;

FIG. 5 is a fragmentary sectional view through the sampling head taken generally along the line 5-5 of FIG. 3 and in the indicated direction;

FIG. 6 is a diagrammatic view illustrating the relationship between the two valve blocks of the sampling head at a first or sample position; and

FIGS. '7A and 7B are diagrammatic views similar to that of FIG. 6 but illustrating the valve blocks in a second or mixing and delivering position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in greater detail, the sampling and mixing apparatus of the invention is shown schematically at 10 in FIG. 1. The apparatus 10 includes a sample head indicated generally at 12 in FIG. 1 and shown in detail in FIG. 2, and a programming device 14 for controlling the automatic operation thereof.

The sample head 12 includes a valve mechanism 16 defined by first and second valve blocks 18 and 20 respectively, linearly movable (slidable) relative to each other between two valve positions, namely, a sample position and a delivery position. The first block 18 has a hollow sample probe 22 extending therefrom which is movable with the sample, head 12 between a first or sample position where thefree end 23 of the probe 22 is inserted into a sample cup or container 24 and a second or retracted position out of the path of travel of the container 24. A piston and cylinder mechanism 26, preferably a pneumatically actuatedcylinder, is connected to the sample head 12 for moving the probe between its two positions and for simultaneously operating the valve mechanism 16 by moving it between its two positions. The cylinder 26 is operated through a valve 28 controlled by the device 14. The valve 28 alternately connects each end of the cylinder 26 to a source 30 of pressure and a source 32 of vacuum.

' In the first position of the probe 22 and the valve mechanism 16 the probe 22 is connected through the valve blocks 18 and 20 and a sample loop 34 to a sample pump 36 for withdrawing some of a liquid sample from the cup 24. The pump 36 is operated by a valve 38 connected to the sources 30 and 32 of pressure and vacuum and controlled by the device'l4. In this way a given amount of sample is drawn, i.e., aspirated from the cup 24 and into the sample loop 34. At the same time, a source 40 of reagent is connected through the valve blocks 18 and 20 to a reagent pump 42 which is operated by a valve 44 connected to the sources 30 and 32 of pressure and vacuum for filling the pump 42 with a quantity of reagent. The valve 44 is also controlled by the device 14.

After a sufficient amount of sample has been drawn through the sample loop 34, the cylinder 26 is operated to move the probe out of the cup 24 and to its retracted position and at the same time to move the valve blocks 18 and 20 relative to each other. This action will shear off and trap a given amount (volume) of sample in the sample loop 34 while moving the blocks 18 and 20 to the second valve position.

When the valve mechanism 16 is in the second or delivery position, one end of the sample loop 34 is connected through the valve blocks 18 and 20 to the reagent pump 42 which is now operated by the device 14 to pump reagent therefrom into the valve blocks 18 and 20. The other end of the sample loop 34 is then connected to a conduit or tubing 50 leading to a receptacle 52, such as a reaction test tube. A shunt passage hereinafter to be described in detail shunts some of the reagent around the sample loop 34 to the outlet end of the loop 34 where it mixes with the sample being ejected from the sample loop 34 by the pressure of the reagent stream at the inlet end of the loop 34. In this way, the given amount of sample is simultaneously ejected from the sample loop 34, mixed with the reagent and delivered in a reagent-sample mixture to the reaction test tube 52. In the tube 52, the reagent reacts with the liquidsample and after a predetermined period of time the resulting mixture may be subjected to colorimetric measurements. In the case of straight dilution, the resulting mixture may be subjected to counting, etc.

At the same time the probe 22 and the outlet of the sample pump 36 are connected to a source of scavenge vacuum 54 for vacuum scavenging liquid sample material therefrom to prepare the apparatus 10 for taking another sample.v

As shown in FIG. 2, the sample head l2-includes an arm 56 having one end 58 mounting the valve mechanism'l6 and another end 60 pivotally connectedat 57 to the supporting structure or post 62. Preferably, and as shown in FIG. 3, the arm 56 includes two parallel spaced plates 64 and 66 with the valve mechanism 16 mounted therebetween. In the illustrated embodiment, the block 18 is secured to and between the plates 64 and 66 by screws 65 (FIG. 3) and the second valve block 20 is positioned between the plates 64 and 66 for slidably engaging the block 18. As a result, the plates 64 and 66 form a guideway for the block 20 and prevent lateral movement of the block 20.

The air cylinder 26 is pivotally connected at 67 to the supporting structure 62 and at 69 to the arm 56 between the ends 58 and 60 thereof. In FIG. 2, the sample head 12 is shown in the first or sample position and in phantom lines in the second or retracted position.

As will be described in detail in connection with the description of FIGS. 6 78, each of the valve blocks 18 and 29 has ports therein for effecting the various connections, described above, when the blocks 18 and 20 are in the sample position or in the delivery position.

As best shown in FIG. 5, the first block 18 has an inner face 68 and an outer face 70. Likewise, the second valve block 20 has an inner face 72 and an outer face 74. According to the teachings of the present invention, the fluid connections are made and broken at the inner faces 68 and 72 of the blocks 18 and 20 which are held in tight sliding engagement. To provide a good seal between the inner faces 68 and 72 in the areas adjacent the port connections between the blocks 18 and 20, the blocks 18 and 20 are compressively loaded and the inner faces 68 and 72 are ground and lapped. Preferably, the inner faces 68 and 72 are formed from a very hard material which is ground and polished smooth to inhibit, if not prevent, galling of the inner faces 68 and 72. Because of the pressure loading the blocks must be made from a material having high dimensional stability. Also, the material must be highly resistant to corrosion from the fluids passed therethrough. In one embodiment of the invention, the first block 18 is made of graphite and the second block 20 is made of stainless steel with the inner face 72 flame or plasma-sprayed with an aluminum oxide silicon oxide composition.

As best shown in FIG. 2, a linkage mechanism extends between the valve mechanism 16 and the supporting structure 62. The linkage mechanism engages the second block 20 at one end and the supporting structure 62 at the other end and serves a dual purpose.

First, the linkage mechanism 76 effects movement of the block 20 relative to the block 18 when the arm 56 is swung around the pivot 57 and second, provides the compressive loading which urges the block 20 against the block 18. With respect to the latter, the linkage mechanism 76 includes an elongated flat bar 78 which functions as a cantilever spring arm. The bar 78 has pivot members 79 adjustably screwed therein at one end thereof with the pointed ends of members 79 engaged in sockets in the upper or outer surface 74 of the second block 20 as best shown in FIG. 5 and the other end of the bar 78 has a suitable threaded aperture in which is received a screw-threaded pivot member 80. The pivot member 80 pivotally engages the supporting structure 62. The bar 78 is positioned between the plane of the outer face 74 of the second block 20 and a roller 82 (FIGS. 2 and 4) which is mounted between the plates 64 and 66 and functions as a rolling fulcrum. The roller 82 is in pressure-engagement with the bar 78 and the pressure can be adjusted by turning the pivot member 80 to move the end thereof toward and away from the bar 78. The pressure exerted by the roller 82 is transmitted in cantilever fashion through the bar 78 by way of pivot members 79 against the block 20 to urge the same against the block 18 and in this manner maintain the desired sealing engagement between inner faces 68 and 72 of the blocks 18 and 20. The roller 82 also permits easy movement of the bar relative to the roller. In this respect, when the arm 56 is moved upwardly, the bar 78 is moved upwardly, also sliding slightly, and the roller 82 rolls along the upper surface of the bar 78 all the while maintaining pressure on the bar 78.

As shown in FIG. 2, the block 20 is longer than the block 18. Movement of the block 20 relative to the block 18 is precisely limited by stop members 84 and 86 secured respectively to the ends of the block 20 in position to engage the ends of the block 18. Thus, when the arm 56 is moved downwardly by the cylinder 26, movement of the arm 56 is limited by engagement of the stop member 84 with one end of the valve block 18. Likewise, when the arm 56 is moved upwardly by the cylinder 26, movement thereof is limited by engagement of the stop member 86 with the other end of the block 20. The positions of engagement between the stop members 84 and 86 and the respective ends of the block 20 also define the first and second valve positions of the valve mechanism 16.

Turning now to FIG. 6, the first valve block 18 has a number of galleries and passageways therein which are identified as follows: a sample pickup passageway 90 extending between the faces 68, 70 of the block 18 and connected at the outer face 70 to the aspirating probe 22; a sample extraction passageway 92 extending between the faces 68, 70 and connected at the outer face 70 to a tube or conduit 93 leading to the sample pump 36; a reagent supply passageway 94 extending between the faces 68,70 and connected at the outer face 70 to a conduit 95 leading to the source 40 of reagent; a first reagent transfer passageway 96 opening only to the inner face 68; a second reagent transfer passageway 98 also opening only to the inner face 68; a sample delivery passageway 100 extending between the faces of the block 18 and connected at the outer face 70 to the conduit 50; a gallery 102 connecting the first transfer passageway 96 with the second transfer passageway 98; and a shunt gallery 103 connecting the gallery 102 with the sample delivery passageway 100.

The second block 20 also has a number of passageways and a gallery therein which are identified as follows: first and second passageways 104 and 106 which extend between the faces 72,74 of the block 20 and which form part of the sample loop 34; a reagent delivery passageway 108 which extends between the faces 72,74 of the block 20 and which is connected at the outer face 74 to a conduit 109 leading to the reagent pump 42; a first evacuation passageway 110 extending between the faces of the block 20 and connected at the outer face to a conduit 111 leading to the source 54 of scavenge vacuum; a second evacuation passageway 112 which opens only to the inner face 72; and a gallery 114 connecting the first evacuation passageway 110 with the second evacuation passageway 112.

The passageways all extend normal to the faces of the blocks 18, 20 and preferably are located on the longitudinal centerline of each block 18,20.

In FIG. 6, the valve blocks 18,20 are in the first or sample position. In this position, the port of the sample pickup passageway 90 is aligned and in communication with the port of the first passageway 104 of the sample loop 34, the port of the second passageway 106 being aligned and in communication with the sample extraction passageway 92 connected by the conduit 93 to the pump 36. At this time, the programming device 14 has operated the valve 38 to cause the pump 36 to extract or aspirate some of the sample fluid from the sample cup 24 through the probe 22. The sample fluid is drawn part way into the conduit 93 but not into the pump 36 because the pump 36 is of the displaceable diaphragm type, with limited volume movement. Also, at this time, the reagent supply passageway 94 is aligned and in communication with the reagent delivery passageway 108 and the valve 44 has been operated by the device 14 to cause reagent pump 42 to draw a quantity of reagent from the reagent source 40 into the pump 42.

After a predetermined time as determined by the programming device 14, the valve 28 is actuated to operate the cylinder 26 to move the sample head 12 to the second or delivery position. At the same time the valves 38 and 44 are actuated to reverse the operations of the pumps 36 and 42 so that in the second valve position which is shown in FIGS. 7A and 7B the pumps 36 and 42 urge fluid toward the valve mechanism 16.

It will be appreciated that when the valve blocks 18,20 are moved relative to each other as the valve mechanism 16 is moved to its second position, the port openings of the first and second passageways 104 and 106 of the sample loop 34 at the inner face 72 at the block 20 are sheared so as to trap a given volume of sample in the sample loop 34.

In the second position of the valve mechanism 16 and as shown in FIG. 7A, the reagent delivery passageway 108 is now aligned and in communication with the first reagent transfer passageway 96. At the same time, the second reagent transfer passageway 98 communicates with the first passageway 104 of the sample loop 34, i.e., communicates with the 'inlet port of the sample loop 34; and the second passageway 106 of the sample loop 34, i.e., the outlet port of the sample loop 34, communicates with the'sample delivery passageway 100.

Preferably, the shunt gallery 103 which extends between the second reagent transfer passageway 98 and the sample delivery passageway 100 has a different cross section (diameter) than the sample loop 34. In this respect, the sample loop 34 preferably has a maller cross section than the shunt gallery 103 so that a fraction of the reagent flows through the sample loop 34 rejoining the major reagent stream at the junction of the shunt gallery with the sample delivery passageway 100. At this junction the sample material is intermingled with the reagent stream so that the fluid emerging from the end of the delivery tube 50 comprises a mixture of sample and reagent. It is to be noted that the shunt gallery 103 has three functions.

First, it avoids passing the entire reagent stream through the sample loop 34. Since the loop 34 is of smaller cross section than the gallery 102, the loop 34 presents a higher impedance to fluid flow. However, the shunt gallery 103 prevents an undesirable high impedance to the flow of reagent through the sample loop 34 by providing a bypass or shunt for the flow of reagent.

Second, the proportions of the reagent passing through the shunt gallery 103 and the sample loop 34 are controlled by the relative sizes of the sample loop 34 and the shunt gallery 103. By proper selection of the cross section (diameter) of the shunt gallery 103 relative to the cross section of the sample loop 34, oen can produce optimum intermingling of sample and reagent at the junction of the shunt gallery 103 with the sample delivery passageway 100.

Third, by minimizing the flow of reagent through the sample loop 34, damage to fragile elements such as blood cells in the sample material is avoided. In this respect. the relativey gentle flow of fluid through the shunt gallery minimizes damage to those elements which could be caused by high stream velocities and turbulent flow in a "straight through" system.

At the same. time that reagent is being mixed'with the sample and is forcing the sample into the delivery conduit 50, the sample pickup passageway 90 and the sample extraction passageway 92 are being evacuated by the scavenge vacuum device 54. In this respect and as best shown in FIG. 7B, the sample pickup passageway 90 is now aligned and in communication with the second evacuation passageway 112 and the sample extraction passageway 92 is now aligned and in communication with the first evacuation passageway 110. Thus, in

the second valve position, the scavenge vacuum device 54 extracts or evacuates most of the sample left in the passageway (and the probe 22 connected thereto) and in the extraction passageway 92 (and the conduit 93 connected thereto). Also, the vacuum acting through conduit 93 on pump 36 cooperates with the pressure supplied through valve 38 to pump 36 to return the same to its extracting position. As a result, the sample head 12 will be ready to pick up another sample when it is moved back to its first position.

The port opening of each passageway at the outer face 72 or 74 of the respective valve block 18 or 20 is counter bored to receive an end of a metal pipe which is secured therein with an epoxy cement. Some of these connections are shown in FIG. 5. Except for the one pipe defining the probe 22, the pipes are cut short to form suitable quick-connect-disconnect fittings for detachably receiving thereon the ends of plastic tubings defining the various conduits.

As best shown in FIG. 2, the sample loop 34 includes a length of such tubing which is detachably connected to two of the fittings which are identified with reference numerals 118 and 120 and which are secured to the outer face 74 of the second block 20 and in communication respectively with the passageways 104 and 106. Since the ends of the length 116 of tubing are merely passed onto the fittings 118, 120, the volume of the sample loop 34 can be changed very easily merely by changing the length 116 of tubing.

As shown in FIG. 5, two of the fittings, namely, the figures which are identified with reference numerals 122 and 124 and which form respectively, extensions of passageways 108 and 110 for detachably connecting conduits 109 and 111 thereto, extend respectively through openings 126 and 128 in thebar 78. The openings 126 are larger than the fittings 122 and 124 to permit movement of the bar 78 laterally of and relative to the fittings 122 and 124 during movement of the sample head 12 between its two positions.

It will be apparent from the foregoing description that obvious modifications and variations can be made to the sample pickup and mixing apparatus of the present invention and the novel sample head thereof without departing from the spirit and scope of the invention. For example, the apparatus 10 can be used for diluting a sample in which case the source 40 is a source of diluent. Accordingly, the scope of the invention is only to be limited as necessitated by the accompanying claims.

What it is desired to secure by Letters Patent of the United States is:

l. A'sample head for use at a sample pickup station, said head comprising a hollow sample pickup probe adapted to be inserted into a sample container at a sample pickup station for extracting a given amount of fluid sample from the container, said pickup probe being movable between a first or sample position and a second or retracted position, valve means operable upon movement of said probe to said sample position for connecting said probe to means for withdrawing fluid from the sample container through said probe, and means for moving said probe and simultaneously operating said valve means whereby said valve means is operated by said moving means to connect said probe to the withdrawing means at the same time said probe is moved by said moving means to said sample position.

2. The sample head as claimed in claim 1 including arm means pivotally mounted to a supporting structure for supporting said sample pickup probe and said valve means in spaced relationship to the supporting structure.

3. The sample head as claimed in claim 2 wherein said moving means is connected to said arm means.

4. The sample head as claimed in claim 2 wherein said arm means includes a pair of parallel spaced arm plates pivotally connected to the supporting structure and having said valve means mounted therebetween.

5. The sample head as claimed in claim 4 wherein said valve means includes first and second valve blocks each having at least one passageway therein, said first block being secured to and between said plates and said second block being movably mounted between said plates adjacent and in sliding contact with said first block, said plates forming a guideway for said second block preventing lateral movement thereof.

6. The sample head as claimed in claim 2 wherein said valve means includes first and second valve blocks each having at least one passageway therein, said first block being secured to said arm means and said second block being movably mounted on said arm means in sliding contact with said first block.

7. The sample head as claimed in claim 6 including stop means for limiting relative movement between said valve blocks.

8. The sample head as claimed in claim 7 wherein said second block is longer than said first block and said stop means includes stop members which extend from each end of said second block and which are adapted to engage respective ends of said first block and thereby stop movement of said second block relative to said first block upon movement of said valve means to said first or second valve position said stop means also serving to limit movement of said arm means by said moving means such that engagement of said first block with one of saidstop members defines said first or sample position and engagement of said first block with said other stop member defines said second or retracted position.

9. The sample head as claimed in claim 6 wherein said sample head includes a linkage mechanism having first and second ends, said first end of said linkage mechanism engaging said second block and said second end of said linkage mechanism engaging the supporting structure whereby, when said first block is moved upon movement of said arm means by said moving means, said linkage mechanism causes said second block to move relative to said first block and between said valve positions.

10. The sample head as claimed in claim 9 wherein a roller is connected to said arm means and spaced from said second block a predetermined distance opposite the engagement thereof with said first block and said linkage mechanism includes a bar which extends through the space between said roller and said second block. said roller applying pressure to said bar which is transmitted by the first end of said linkage mechanism against said second block for urging saidsecond block into tight sliding engagement with said first block.

11. The sample head as claimed in claim 9 wherein said linkage mechanism includes at least one pivot means mounted at one end thereof for pivotally engaging said second block or the supporting structure.

12. The sample head as claimed in claim 10 wherein at least one pivot means is adjustably mounted at one end of said bar whereby the position of the pivot end of said pivot means from the plane of said bar can be adjusted as desired for increasing or decreasing the pressure between said roller and said bar.

13. The sample head as claimed in claim 1 wherein said valve means include first and second valve blocks movable relative to each otherv 14. The sample head as claimed in claim 13 wherein each of said valve blocks has a smooth hard face which slidably engages the smooth hard surface on the other block, and said hard surface on each block is formed of an aluminum oxide silicon oxide composition.

15. The sample head as claimed in claim 13 wherein at least one of said blocks is made of graphite.

16. The sample head as claimed in claim 13 including means for urging said valve blocks into face to face sliding engagement with each other.

17. The sample head as claimed in claim 13 wherein said first block has a sample pickup passageway therein and said probe is connected to said first block and in communication with said sample pickup passageway, said valve means connecting said passageway to the means for withdrawing fluid sample from the container when said valve means is in said first position 18. The sample head as claimed in claim 17 wherein said second block has means for connecting said passageway to the means for withdrawing fluid from the container.

19. The sample head as claimed in claim 18 wherein said connecting means includes a sample loop having at least a portion thereof extending through said second block.

20. The sample head as claimed in claim 19 wherein at least a portion of said sample loop is external of said blocks.

21. The sample head as claimed in claim 19 wherein said second block has first and second passageways therein forming at least a part of said sample loop.

22. The sample head as claimed in claim 21 wherein said second block has at least two fittings connected thereto, one in communication with said first passageway and the other in communication with said second passageway, said fittings being adapted to detachably receive thereon the ends of a length of tubing which can be easily changed to adjust the length of said sample loop.

23. The sample head as claimed in claim 21 wherein said first block has a sample extraction passageway extending therethrough, the port opening of said sample extraction passageway opening to the outer surface of said first block being adapted to be connected to the means for withdrawing fluid from the sample container and the port opening of said sample extraction passageway opening to the surface of said first block which engages said second block being arranged to be aligned and in communication with said second passageway when said valve means is in said first position.

24. The sample head as claimed in claim 21 wherein said first and second passageways of said sample loop are closed as said valve blocks are being moved relative to each other to a second valve position to trap a given amount of sample in said loop and said first block has a sample delivery passageway therein arranged so as to be aligned and in communication with said second passageway in said second block when said valve means is in said second position for delivering said given amount of sample trapped in said sample loop to a receptacle.

25. The sample head as claimed in claim 24 wherein said valve means includes means for connecting a source of fluid to said sample loop when said valve means is in said second position, said fluid connecting means including a gallery in said first block with at least one port opening to the inner face of said first block, said port being arranged so as to be aligned and in communication with said first passageway in said second block when said valve means is in said second position so that fluid can flow into said first passageway to force said given amount of liquid sample therefrom and out of said valve means through said sample delivery passageway.

26. The sample head as claimed in claim 25 wherein said first block has a shunt gallery therein between said first mentioned gallery and saidsample delivery passageway for bypassing some of said fluid around said sample loop and into said given amount of said liquid sample flowing through said sample delivery passageway thereby to mix fluid with said given amount of sample as it is being ejected from said sample loop.

27. The samplehead as claimed in claim 26 wherein said shunt gallery has a cross section larger than the cross section of said sample loop.

28. The sample head as claimed in claim 17 wherein said second blockincludes means which communicates with said sample pickup passageway in said first block when said valve means is in said second position for connecting said sample pickup passageway and said hollow sample probe connected thereto with means for evacuating same.

29. The sample head as claimed in claim 23 wherein said second block has passage means therein which communicates with said sample extraction passageway when said valve means is in said second position for connecting said sample extraction passageway with means for evacuating same. 

1. A sample head for use at a sample pickup Station, said head comprising a hollow sample pickup probe adapted to be inserted into a sample container at a sample pickup station for extracting a given amount of fluid sample from the container, said pickup probe being movable between a first or sample position and a second or retracted position, valve means operable upon movement of said probe to said sample position for connecting said probe to means for withdrawing fluid from the sample container through said probe, and means for moving said probe and simultaneously operating said valve means whereby said valve means is operated by said moving means to connect said probe to the withdrawing means at the same time said probe is moved by said moving means to said sample position.
 2. The sample head as claimed in claim 1 including arm means pivotally mounted to a supporting structure for supporting said sample pickup probe and said valve means in spaced relationship to the supporting structure.
 3. The sample head as claimed in claim 2 wherein said moving means is connected to said arm means.
 4. The sample head as claimed in claim 2 wherein said arm means includes a pair of parallel spaced arm plates pivotally connected to the supporting structure and having said valve means mounted therebetween.
 5. The sample head as claimed in claim 4 wherein said valve means includes first and second valve blocks each having at least one passageway therein, said first block being secured to and between said plates and said second block being movably mounted between said plates adjacent and in sliding contact with said first block, said plates forming a guideway for said second block preventing lateral movement thereof.
 6. The sample head as claimed in claim 2 wherein said valve means includes first and second valve blocks each having at least one passageway therein, said first block being secured to said arm means and said second block being movably mounted on said arm means in sliding contact with said first block.
 7. The sample head as claimed in claim 6 including stop means for limiting relative movement between said valve blocks.
 8. The sample head as claimed in claim 7 wherein said second block is longer than said first block and said stop means includes stop members which extend from each end of said second block and which are adapted to engage respective ends of said first block and thereby stop movement of said second block relative to said first block upon movement of said valve means to said first or second valve position , said stop means also serving to limit movement of said arm means by said moving means such that engagement of said first block with one of said stop members defines said first or sample position and engagement of said first block with said other stop member defines said second or retracted position.
 9. The sample head as claimed in claim 6 wherein said sample head includes a linkage mechanism having first and second ends, said first end of said linkage mechanism engaging said second block and said second end of said linkage mechanism engaging the supporting structure whereby, when said first block is moved upon movement of said arm means by said moving means, said linkage mechanism causes said second block to move relative to said first block and between said valve positions.
 10. The sample head as claimed in claim 9 wherein a roller is connected to said arm means and spaced from said second block a predetermined distance opposite the engagement thereof with said first block and said linkage mechanism includes a bar which extends through the space between said roller and said second block, said roller applying pressure to said bar which is transmitted by the first end of said linkage mechanism against said second block for urging said second block into tight sliding engagement with said first block.
 11. The sample head as claimed in claim 9 wherein said linkage mechanism includes at least one pivot means mounted at one end thereof for pivotally engaging said seconD block or the supporting structure.
 12. The sample head as claimed in claim 10 wherein at least one pivot means is adjustably mounted at one end of said bar whereby the position of the pivot end of said pivot means from the plane of said bar can be adjusted as desired for increasing or decreasing the pressure between said roller and said bar.
 13. The sample head as claimed in claim 1 wherein said valve means include first and second valve blocks movable relative to each other.
 14. The sample head as claimed in claim 13 wherein each of said valve blocks has a smooth hard face which slidably engages the smooth hard surface on the other block, and said hard surface on each block is formed of an aluminum oxide - silicon oxide composition.
 15. The sample head as claimed in claim 13 wherein at least one of said blocks is made of graphite.
 16. The sample head as claimed in claim 13 including means for urging said valve blocks into face to face sliding engagement with each other.
 17. The sample head as claimed in claim 13 wherein said first block has a sample pickup passageway therein and said probe is connected to said first block and in communication with said sample pickup passageway, said valve means connecting said passageway to the means for withdrawing fluid sample from the container when said valve means is in said first position.
 18. The sample head as claimed in claim 17 wherein said second block has means for connecting said passageway to the means for withdrawing fluid from the container.
 19. The sample head as claimed in claim 18 wherein said connecting means includes a sample loop having at least a portion thereof extending through said second block.
 20. The sample head as claimed in claim 19 wherein at least a portion of said sample loop is external of said blocks.
 21. The sample head as claimed in claim 19 wherein said second block has first and second passageways therein forming at least a part of said sample loop.
 22. The sample head as claimed in claim 21 wherein said second block has at least two fittings connected thereto, one in communication with said first passageway and the other in communication with said second passageway, said fittings being adapted to detachably receive thereon the ends of a length of tubing which can be easily changed to adjust the length of said sample loop.
 23. The sample head as claimed in claim 21 wherein said first block has a sample extraction passageway extending therethrough, the port opening of said sample extraction passageway opening to the outer surface of said first block being adapted to be connected to the means for withdrawing fluid from the sample container and the port opening of said sample extraction passageway opening to the surface of said first block which engages said second block being arranged to be aligned and in communication with said second passageway when said valve means is in said first position.
 24. The sample head as claimed in claim 21 wherein said first and second passageways of said sample loop are closed as said valve blocks are being moved relative to each other to a second valve position to trap a given amount of sample in said loop and said first block has a sample delivery passageway therein arranged so as to be aligned and in communication with said second passageway in said second block when said valve means is in said second position for delivering said given amount of sample trapped in said sample loop to a receptacle.
 25. The sample head as claimed in claim 24 wherein said valve means includes means for connecting a source of fluid to said sample loop when said valve means is in said second position, said fluid connecting means including a gallery in said first block with at least one port opening to the inner face of said first block, said port being arranged so as to be aligned and in communication with said first passageway in said second block when said valve means is in said second position so that fluid can flow into said first passageway to force said given amount of liquid sample therefrom and out of said valve means through said sample delivery passageway.
 26. The sample head as claimed in claim 25 wherein said first block has a shunt gallery therein between said first mentioned gallery and said sample delivery passageway for bypassing some of said fluid around said sample loop and into said given amount of said liquid sample flowing through said sample delivery passageway thereby to mix fluid with said given amount of sample as it is being ejected from said sample loop.
 27. The sample head as claimed in claim 26 wherein said shunt gallery has a cross section larger than the cross section of said sample loop.
 28. The sample head as claimed in claim 17 wherein said second block includes means which communicates with said sample pickup passageway in said first block when said valve means is in said second position for connecting said sample pickup passageway and said hollow sample probe connected thereto with means for evacuating same.
 29. The sample head as claimed in claim 23 wherein said second block has passage means therein which communicates with said sample extraction passageway when said valve means is in said second position for connecting said sample extraction passageway with means for evacuating same. 